JPS61197876A - Manufacture of plastic pipe and manufacture of composite pipe using said plastic pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industry B, Field of Application of L) The present invention provides a method for manufacturing a plastic tube with a smooth inner circumferential surface and no unevenness, and a method for manufacturing a plastic tube with a smooth inner circumferential surface and no unevenness, and a method for manufacturing a plastic tube by coating the outer circumferential surface of this plastic tube with a metal tube to increase rigidity. The present invention relates to a method for manufacturing a composite pipe with improved performance, and in particular to a method for manufacturing a pipe suitable as a piping material for an IBIIli water system for cleaning electronic parts such as semiconductors.

(Prior art) In general, plastic pipes such as vinyl chloride resin and polyethylene resin are melted through an annular resin passage provided between a die ring of the extruder, a die ring of the extruder, and a mandrel. These plastic pipes are manufactured by extruding thermoplastic resin, and these plastic pipes are used as piping materials for water and sewage systems, as well as gas supply piping materials, etc.

In addition, although these plastic pipes have excellent corrosion resistance, they have poor impact resistance, so depending on the purpose and application, the outer circumferential surface of the plastic pipe is covered with a metal pipe. Various methods for manufacturing this composite pipe have been proposed in the past.

(Problem to be solved by the invention) In recent years, technological innovation has been remarkable in the field of electronics, and with this, high performance and high quality electronic components are required. Cleaned with equipment.

Plastic pipes have come to be used as piping materials for ultrapure water equipment, but plastic pipes obtained by conventional methods do not have smooth inner surfaces and have minute irregularities, so the inner surface of the pipes is uneven. There were problems such as the accumulation of impurities, the growth of bacteria, and the adhesion of algae.

The present invention provides a method for manufacturing a plastic tube with a smooth inner circumferential surface and no unevenness, and a composite tube with improved rigidity and excellent impact resistance by covering the outer circumferential surface of this plastic tube with a metal tube. In particular, these pipes can be suitably used as piping materials for ultrapure water equipment.

(Means for Solving the Problems) The present invention provides an annular resin passage between a goo and a mandrel, and passes a molten thermoplastic synthetic resin through the M resin passage to manufacture a plastic snack tube. A heating device is built into the mandrel, and the heating device heats the inner peripheral surface of the tube formed into an annular shape while extrusion molding is performed.

In addition, the method for manufacturing a composite pipe of the present invention includes applying a foaming adhesive to the outer peripheral surface of the plastic pipe obtained by the above manufacturing method,
This plastic tube is inserted into a metal tube to foam the adhesive.

Furthermore, another method for manufacturing composite tubes involves inserting the plastic tube obtained by the above-mentioned manufacturing method into a metal tube having an inner diameter slightly larger than the outer diameter of the protective tube, and reducing the diameter of the metal tube to reduce its inner peripheral surface. This method involves coating the outer circumferential surface of a plastic pipe by bringing it into contact with the outer circumferential surface of the pipe.

EMBODIMENT OF THE INVENTION Hereinafter, the specific structure of this invention is demonstrated in detail based on an Example.

(Example) FIG. 1 is a longitudinal cross-sectional view showing the manufacturing process of the plastic pipe of the present invention, in which reference numeral 1 represents a die ring and 2 represents a mandrel.

An annular resin passage through which the molten resin passes is provided between the die ring 1 and the mandrel 2. Inside the mandrel 2, a heating device 1- such as a heater or a jacket through which a heating medium circulates is installed. 1 is provided.

A die device consisting of a die ring 1 and a mandrel 2 is provided at the tip of the extruder, and a nizing former 3 and cooling water WI4 are provided in front of this die device.

The manufacturing method of the plastic tick tube of the present invention is such that when the molten thermoplastic resin extruded from the extruder passes through the resin passage between the die ring 1 and the mandrel 2 and is formed into an annular shape, the tube is formed into a ring shape. The inner circumferential surface is extruded while being heated with a heating device HH.

When the inner circumferential surface of the tube passing through the resin passage is heated by the heating device H, the flow characteristics of the resin on the inner circumferential side of the tube improve, and as a result, contact with the outer circumferential surface of the mandrel 2 is performed smoothly, and as a result, the inner circumferential surface is heated. A plastic tube P with no unevenness is extruded. The outer diameter of this plastic IP is then regulated by a sizing former 3, and then guided to a cooling water tank 4 where it is cooled and solidified, and then collected by a collection m<not shown).

The plastic tube thus obtained has a smooth inner circumferential surface and no unevenness, so it can be suitably used as a piping material for ultrapure water equipment as it is.

The thermoplastic resin used in the present invention is preferably a vinyl chloride resin mixed with tin, and this molten resin is extruded at a lower extrusion speed than the extrusion speed used for forming ordinary plastic pipes. Then, the smoothness is further improved, and it is possible to reduce the unevenness of the inner circumferential surface of the tube to 1 or less.

FIG. 2 is a longitudinal sectional view of a composite tube in which the outer peripheral surface of the plastic tube is covered with a metal tube.

This composite tube is made of plastic f! obtained through the above manufacturing process. After applying room-temperature foaming adhesive A evenly on the outer peripheral surface of Ip and inserting it into the metal tube F, apply the adhesive A
It is obtained by foaming and filling the space between the plastic pipe P and the metal ff1F.

Since the outer circumferential surface of the plastic tube P is reinforced with the metal tube F, this composite tube is particularly suitable as a piping material for parts that are susceptible to external forces such as Wis.

In addition, the foamable adhesive used in this manufacturing method includes:
A two-component adhesive in which a polyurethane resin and an isocyanate resin are bonded to each other to form a polyurethane resin is suitable.

FIG. 3 is a longitudinal sectional view showing another manufacturing process of the composite pipe of the present invention.

This composite tube is made by converting the plastic tube obtained through the above manufacturing process into a metal tube having an inner diameter slightly larger than the outer diameter of the protective tube.
This is passed through the forming die 5 to form the metal tube F.
The inner peripheral surface of the metal tube F, which has been reduced in diameter, is made into a plastic tube P.
It is obtained by contacting the outer circumferential surface of the

In this manufacturing process, it is important to reduce the diameter of the metal tube without deforming the plastic tube, so apply an appropriate thickness of adhesive to the outer circumferential surface of the plastic tube in advance, and then apply it inside the metal tube. It is preferable to insert the metal tube and reduce the diameter of the metal tube.

The composite pipe thus obtained is connected sequentially through appropriate pipe joints, but after the manufacturing process of this composite pipe is completed, a flange is provided on the outer periphery of the end of the metal pipe, and the flange surface is It is preferable to cover the protruding inner layer plastic pipe by flange processing, since the flange connection can be easily and reliably performed.

(Operations and Effects of the Invention) The method for manufacturing a plastic pipe of the present invention is such that when extruding molten resin from a resin passage between a die ring and a mandrel and molding it into an annular shape, a heating device built into the mandrel is used to
Since extrusion molding is performed while heating the inner circumferential surface of the tube, the flow characteristics of the molten resin on the inner circumferential side are improved and contact with the outer circumferential surface of the mandrel is made smoothly, resulting in an extremely smooth inner circumferential surface with fine particles. A plastic tube without unevenness can be obtained. Therefore, this plastic tube can be particularly suitably used as a piping material for ultrapure water equipment for cleaning electronic parts such as semiconductors.

Further, the method for manufacturing a composite pipe of the present invention includes inserting the outer peripheral surface of the plastic pipe obtained by the above manufacturing method into a metal pipe,
Because it coats plastic pipes without deforming them,
A tube that not only has a smooth inner circumferential surface but also has excellent rigidity and impact resistance can be obtained.

Moreover, manufacturing this composite tube requires only a device to apply adhesive to the outer circumferential surface of the plastic tube or a molding die to reduce the diameter of the metal tube, so there is no need to make any special arrangements. Since no equipment is required, manufacturing is extremely simple and rapid, and product costs can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing the manufacturing process of the plastic pipe of the present invention, Fig. 2 is a longitudinal sectional view of the composite pipe obtained by the invention, and Fig. 3 is a longitudinal sectional view showing the manufacturing process of the composite pipe of the invention FIG. 1... Die ring 2... Mandrel 3... Sizing former 4... Cooling water N 5... Forming die P
...Plastic pipe F...Metal pipe v'g, old procedure amendment IJ (spontaneous) April 1985 Q mouth G + application No. 1983-37051 2 Name of the invention Plus book pipe Buddha making and composite pipe manufacturing method using this plastic pipe 3 Corrected δ Relationship with fact f1 Name of patent applicant (017) Mitsubishi Plastics Co., Ltd. 4 Representative Address 2-5 Marunouchi, Chiyoda-ku, Tokyo [Detailed Description of the Invention J-6 Contents of Amendment in Specification No. 2]

Claims (1)

[Scope of Claims] 1. An annular resin passage is provided between a die ring and a mandrel, and when extruding a plastic pipe by passing a molten thermoplastic resin through the resin passage, a heating device is provided on the mandrel. A method for manufacturing a plastic tube, characterized in that extrusion molding is carried out while heating the inner peripheral surface of the tube formed into an annular shape using the heating device. 2. An annular resin passage is provided between the die ring and the mandrel, and when extruding a plastic pipe by passing a molten thermoplastic resin through the resin passage, a heating device is built into the mandrel to heat the thermoplastic resin. A plastic tube is extruded while heating the inner circumferential surface of the tube formed into an annular shape using a device, and then a foaming adhesive is applied to the outer circumferential surface of the plastic tube, and the plastic tube is inserted into the metal tube. A method for manufacturing a composite pipe characterized by foaming adhesive and filling the space between a plastic pipe and a metal pipe. 3. An annular resin passage is provided between the die ring and the mandrel, and when extruding a plastic pipe by passing a molten thermoplastic resin through the resin passage, a heating device is built into the mandrel to heat the thermoplastic resin. A plastic tube is extruded while heating the inner peripheral surface of the tube formed into an annular shape using a device, and then the plastic tube is inserted into a metal tube having an inner diameter slightly larger than the outer diameter of the tube, and then the metal tube is shrunk. A method for manufacturing a composite tube, characterized in that the inner circumferential surface of the composite tube is brought into contact with the outer circumferential surface of a plastic tube.